1. Field of the Invention
The invention relates to a laser oscillator which is provided with a blower.
2. Description of the Related Art
Known in the art is a laser oscillator which is provided with a blower wherein a rotation speed detection device such as a taco generator or encoder is used to detect the rotation speed of the blower in an idling state and wherein a rotation command value which is transmitted to the blower at the time of restart of operation of the blower is made to match with the detected rotation speed (for example, Japanese Patent Publication No. 3-218083A, Japanese Patent Publication No. 3-246982A, and Japanese Patent Publication No. 4-22181A).
From the viewpoint of reducing the power consumption of a laser oscillator, it is preferable to stop the power supply to a drive part of the blower so as to stop the operation of the blower. In this case, the blower starts idling. In order to quickly restart the operation of the idling blower, it is necessary to detect the rotation speed of the idling blower when restarting its operation.
However, according to the prior art, an encoder or other rotation speed detection device is necessary for detecting the rotation speed of the blower, so this leads to an increase of the manufacturing cost of the laser oscillator. Therefore, a technique, which can estimate the rotation speed of the blower in idling in an inexpensive and accurate manner, is required in the art.